Compound shoe construction for floating roof sealing mechanism



June 24, 1958 J. H. WIGGINS 2,840,260

COMPOUND SHOE CONSTRUCTION FOR FLOATING ROOF SEALING MECHANISM 2 Sheets-Sheet 1 Filed Aug. 3, 1955 INVENTOR John H ldzig qirzs' ATTORNEY June 24, 1958 WIGGINS ROOF SEALING MECHANISM Filed Aug. 3, 1955 2 Sheets-Sheet 2 I l" INVENTOR John 15. U/g zns y /w Q ATTORNEY U i ta e f 8 F C I 2,840,260 g g COMPOUND SHOE CONSTRUCTION FOR FLOAT ING ROOF. (SEALING MECHANISM I John H. Wiggins, Woodside, Calif. Application August 3, 1955, Serial NO. 526,117

1 Claim. (Cl. 220-26) My invention relates to improved sealing mechanisms for a floating roof for tanks employed for storing Oil and the like, and which comprises an annular shoe arranged in sliding sealing engagement with the side of the tank with the bottom edge portion of the shoe projecting into the liquid in the tank on which theroof floats, and is con cerned more particularly with'the provision of a com-v pound shoe structure including inexpensive flexible, strong material in the major portion of the sliding "shoe which is above the liquid, and at the lower liquid'contacting section part of the shoe provi'ding a corrosion-resistant structure, the lower corrosion-resistant section being connected in a gas-tight manner tothe uppersection'of the sliding shoe.

It is a general object of the inventionto provide, a sealing mechanism for a floating tank roof structure in which the shoe is of two-part construction. 7

Another general object of the invention is to provide a compound shoe in which'a corrosion-resistant section of the sliding shoe is provided adjacent to the liquid level within the tank to increase the life of thesliding shoe;

Another object of theinvention is to provide'a seal structure of the above character in which a lower section of the corrosion-resistant material is connected to an upper section of conventional steel by a gas-tight joint which includes means for securing the outer periphery of a fabric seal between the sliding shoe and the floating roof.

Another general object of the invention is to provide a sliding shoe for a seal structure in a floating roof in which the circumferential limberness of the shoe is maintained so as to conform readily to irregularities in r mechanism for floating roofs and embodying my invention.

Figure 2 is an enlarged fragmentary view of a portion of Figure 1.

Figure 3 is a vertical sectional view of a sealing mechanism for floating roofs showing another preferred form of my invention.

One of the principal characteristics of Sliding shoe seals of a cylindrical character in conjunction with floating roof tanks, is that the shoe in order to serve its purpose satisfactorily, must maintain substantial contact with the tank around its periphery, conforming to irregularities around the circumference of the tank, and at the same time provide suflicient strength structurally to support loads imposed by snow, freezing, and accidental causes. This problem has led to the conventional procedure of 2 using thin, inexpensive steel plate about A thick, for this sliding shoe. The principal difliculty with .the thin,

inexpensive steel structure for this sliding shoe is the fact;

that in all oils, the area of maximum corrosion on the size of the shoe and the large circumference of the tanks in wihch it is used, thefabricationofthe entire shoe of a corrosion-resistant material is prohibitive because of the expense. i

In accordance my ion. a a fleas is: e structure, a compound shoe structure is provided in which a lower part or secondary sectionhaving corrosion-resistant qualities is provided, and in which an upper part primary section is made of thin, inexpensive steel for the necessary strength and flexibility inconforrning to the walls of the tank. Preferably also, the shoe is made in two parts which overlap each other, and the fabric seal placed between the lapped portions and clamped securely in place in a gas-tight fashion. nomical'. and satisfactory method of attaching the outer edge of the fabric seal to the sliding shoe structure.-

Referring to the drawings, particularly Figures 12, there is shown a fragmentary section of a cylindrical wall 1 of a storage tank of the kind used extensively through: out the oil industry for storing oil and other volatile liquids. Within the tank 1, a floating roof structure is provided of the conventional tyipe, comprising anouter riin 9 secured and extending upwardly from a. bottom. deck 10, to a top deck 11. To seal thespace between floating roof structure and the outer wall, a seal mecha-' nism is providedincluding asliding cylindrical shoe} comprising a primary upper se'ctiori'Za extending through the major portion of the height of the shoe, and a lower secondary section 2b at the lower portion of the tank adjacent to liquid level 5. V V

The shoe 2' is connected to the rim,9 of theroof by an annular flexible gas impervious curtain or fabric seal 4, which is clamped to the upright wall 9 of the roof by a seal bar 7 and a plurality of nut and bolt connections 8 spaced thereabout providing a gas-tight joint. The outer periphery of the fabric seal 4 is clamped between an offset portion 3 of the upper primary shoe section 2a and the overlapping portion of the lower secondary shoe section 2b by a plurality of suitable nut and bolt fastenings 6, this connection providing a gas-tight joint at the outer periphery of the fabric seal 4.

Referring to Figure 2, the upper section 2a is provided at each nut or stud 6 with a depressed portion having a frusto-conical surface 22, and the lower section 2b of the shoe is provided with a similar mating depressed portion having a frusto-conical surface 23 in which the head of=the bolt 6 is seated. The fabric seal 4 is apertured and clamped between these frusto-conical surfaces.

At a, plurality of points about the periphery of the floating roof structure, pressure and supporting rods '13 are provided, each having a channel piece 12 at the outer end thereof. Each rod 13 has sliding engagement within a pipe 14 in the roof Wall or rim 9. A washer 15 is provided on the rod 13 as an abutment for a compression spring 16 engaged between the washer 15 and the end wall 14a of the pipe 14.

Preferably, the lower section 2b of the overlapping sections of the sliding shoe is corrosion-resistant, either by being constructed of thicker steel so as to resist corrosion by the amount of material present or a suitable corrosion-resistant material ofthinner section is provided so as to be capable of conforming to the irregularities Patented June This provides an ecoa at ur. The lower constructed of thin, stainless steel as the preferred anticorrosionmatcrial, or a suitable anti-corrosion plastic sheet, or of a steel plate coated with plastic.

By providing a compound, shoe of two overlapping sections,;1not, only is, there provided a a suitable point of' anchoragefiorl the outerlpe riphery of the fabric seal 4, ,but there is providedla lower section which is a" minoi ffractionof the total area of. the shoe so. that it constructed economically of expensive corro; don-resistant materiaLjand'l substantially. increase the life otfflifslidi g sho wit i n r the Pointgreatest corrosive activity within the tank,ri. e., at the liquid level therein;

ei'ring toFig for'the-floatinghroof, in which the fiexible fabric seal 4 is attached between the upperedge" of the upright rim 9. of the, iloatingroof and theupper portion'of the shoelby of suitable seal bars 7a in aconventional manner.- ,The ofiset edge 3 of thegupper section 2 of the shoe is secured directly to lower section 2b. Othertheiconstruction istidentical with that described in connection" with Figure 1. Y

' It noted that in each of the" modified structures shown and described herein, "the structural arrangement provides for a corrosion-resistant material at and adjacent to the liquid level in thetank so that maximum life can be obtained at this weakest region of the shoe. Also the form shown so that the scope thereof should be limited'only by the scope of the appended claim.

I claim: t

In va mechanismjor a floating roof for a subbe 3, there is shown a sealing strucsecondary section 2b may be r stantially cylindrical upright tank for storing a liquid having corrosive characteristics, a substantially cylindrical compound sealin'g'sho'e assemblydisposed about'the pe riphery of said roof and spaced radially outwardly therefrom, said sealing shoe assembly including a primary upper shoe section and a secondary lower shoe section each substantially cylindrical in shape andceach in intimate sliding engagement through the major portion of its height with the inner walLsurface of said tank, said-uppershoe section-and said? lower shoe section re spectively constituting major and minor portions of the total height of said sealing shoe assembly, means carried by saidroof and connected to s aid upper shoe section ,for supporting 'and'mai'ntaining said uppershoe section 15 at a substantially constant elevation with respect to said roof and totally above the liquid in said tank, said upper shoe section being formed of mild steel and the lower edge thereof terminating above and adjacent to the liquid in said tank so that said upper shoe section is totally out of direct conta'cf'with' the'liquid in said tank and is thus free of the major corrosive, actions thereof, said lower shoe section being rigidly secured to and supported solely by said upper shoe section and depending therefrom andprojectingfinto the liquid insaid tank, said lower shoe section being formed of stainless steel so that it is not damaged bythe' no'rmaljcorrosive actions of the liquid in saidtank, means for scaling in gas-tight relation the lower portion of said "upper shoe section and the upper portion of said lower shoe section, and a flexible gasimpervious cu'rtainextending betweenvand sealed in gastight relation with said roof and said sealing shoe as sembly. i

i References Cited in the tile of this patent UNITED S ATES PATENTS 2,006,291' 'Kuehn Dec. 29, 1936 2,495,755 f Orr et a1. Jan. 31, 

